February 8-9 Cold Rain Event

[Ji]

It crept south for sure.

http://www.tropicaltidbits.com/analysis/models/?model=nam4km&region=neus&pkg=asnow&runtime=2017020806&fh=36&xpos=0&ypos=352

Track of nam still way further north than euro

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[Jebman]

On Tuesday Dale City hit 70, with Woodbridge managing a warm 73.

Dale City is 62/46 right now. Unbelievable. On Tuesday I enjoyed a jebwalk in summer garb.

Snow is in the forecast, but the ground temps are not exactly frigid.

The northern and western parts of the Mid Atlantic should do well with grassy accumulations Thursday.

We'll see what develops.

[Snowman.]

06z GFS looks better. colder than previous runs. Snow maps still not much.

[MillvilleWx]

RGEM crept south as well with regard to better accumulations. I-70 and north are looking pretty good at this juncture with areas south still in the game, but certainly more dicey, especially once you get down toward the district. Elevation areas south of 70 may still work out (I.E. Damascus, Clarksburg, Rural areas of NE MoCo, Columbia) but even that could be a question mark. It's been mentioned before but watch the trends of the temps across the region today and how they are verifying within guidance. HRRR will finally come into play later on. If you have WeatherBell, using the HRRR regional feature will help track the handling of the 500 vort as well. Should be a fun day of tracking, finally, and hope trends workout for the better. 

[mitchnick]

10 minutes ago, MillvilleWx said:

RGEM crept south as well with regard to better accumulations. I-70 and north are looking pretty good at this juncture with areas south still in the game, but certainly more dicey, especially once you get down toward the district. Elevation areas south of 70 may still work out (I.E. Damascus, Clarksburg, Rural areas of NE MoCo, Columbia) but even that could be a question mark. It's been mentioned before but watch the trends of the temps across the region today and how they are verifying within guidance. HRRR will finally come into play later on. If you have WeatherBell, using the HRRR regional feature will help track the handling of the 500 vort as well. Should be a fun day of tracking, finally, and hope trends workout for the better. 

Well, since Bob is out, it may as well stay all rain in Rockville. 

[Wonderdog]

The King holds firm and the other models are trying to catch up. I like the trend of the overnight runs. Looks as if we would just need a small improvement today to seal the deal.

[mitchnick]

My guess is that what is causing the models to adjust south last minute is now along the Carolina coast. A relatively small low pressure system that was mentioned yesterday and is well depicted on the top radar map at this link. Every run of every model keeps beating down heights along the east coast and that bugger is the culprit methinks. 

http://www.marylandwx.com/radar-data/

[PDIII]

6 hours ago, PivotPoint said:

Id also like to add (using the map as a visual) many times we're dealing with very light rates to overcome marginal temps. One aspect (it appears) will be we at the very least will have good rates at times. Heavy precip that falls in marginal temp setups can still produce in early February.

DC/NOVA crowd may not get the accums this go around, but hey, at least we can reasonably expect some good heavy snow rates to watch for a a couple hours. That's a win this winter and enjoy it. Once it's over you'll be wishing you did!

This basically says that the earlier we switch over to snow, the better we will do. it will be fun to see how this plays out.  I wouldn't be surprised if somebody a couple of miles nw of the cities gets warning level snow.

[attml]

I like it for what it's worth!

 

[Wonderdog]

29 minutes ago, mitchnick said:

My guess is that what is causing the models to adjust south last minute is now along the Carolina coast. A relatively small low pressure system that was mentioned yesterday and is well depicted on the top radar map at this link. Every run of every model keeps beating down heights along the east coast and that bugger is the culprit methinks. 

http://www.marylandwx.com/radar-data/

Any possibility that this ends up like a Miller B event?

[mitchnick]

8 minutes ago, Wonderdog said:

Any possibility that this ends up like a Miller B event?

I don't think we need to debate the Miller A or B thing. The low off the Carolinas effects our system by deepening and pulling down heights in its wake so our low is nudged south. This low off the Carolinas has been on the Euro for several runs and now all the other models have it. The other models are a little late, it appears right now,  in translating its effects.  I think we want it as strong as it can get to force our system south as far as possible.  As today's model runs come out,  I'm going to be comparing the new runs to the old ones and see if my thoughts have merit I.e. stronger off shore low means further south for our system. 

[showmethesnow]

For those that want a somewhat upbeat take for the potential of snow into the cities. Justine does favor the GEM, RGEM models and with their snowier solutions it would explain his somewhat aggressive forecast.

http://news.justinweather.com/2017/02/07/winter-storm-watch-maryland-first-call-snowfall-february-9/

[CAPE]

26 minutes ago, Wonderdog said:

Any possibility that this ends up like a Miller B event?

Its not a miller B, but the way it all comes together it looks to favor places NE of our region. Northern tier counties in MD should see a nice event. For the rest of us, I think we have to wait and see. Its going to be dynamic for a few hours tomorrow am, so likely lots of now-casting.

[BaltimoreWxGuy]

The forecaster this morning for the NWS seems to think they will downgrade watches to advisories. Probably 2-5. Maybe advisories for DC-Balt for 1-2

[BaltimoreWxGuy]

43 minutes ago, showmethesnow said:

For those that want a somewhat upbeat take for the potential of snow into the cities. Justine does favor the GEM, RGEM models and with their snowier solutions it would explain his somewhat aggressive forecast.

http://news.justinweather.com/2017/02/07/winter-storm-watch-maryland-first-call-snowfall-february-9/

Of course he does. That said, clearly the forecast is a high bust one on either side of the spectrum so who really knows

[mitchnick]

10z HRRR at 18 hours

 

[SomeguyfromTakomaPark]

4 minutes ago, mitchnick said:

10z HRRR at 18 hours

 

Was just about to post this, it looks similar, but even a little further south than the RGEM.

[Thanatos_I_Am]

FWIW this is the experimental 36 HR HRRR from 06z. 

[winterymix]

That experimental HRRR looks plausible, it follows climatology and gives

PSU Carroll County land 7".   Book it.

[BaltimoreWxGuy]

2 minutes ago, winterymix said:

That experimental HRRR looks plausible, it follows climatology and gives

PSU Carroll County land 7".   Book it.

It actually does look solid for being experimental. But maybe a little overdone up there 

[NorthArlington101]

Maybe killing myself last night was the sacrifice we needed. I'm still out though. 

Things look cautiously better but given that I'm wearing shorts today and the fact that the model war is continuing when we are basically 12 hours from game time.... screams disappointment. 

[nj2va]

1 minute ago, winterymix said:

That experimental HRRR looks plausible, it follows climatology and gives

PSU Carroll County land 7".   Book it.

That's what I thought too.  I could see it playing it out as depicted based on climo.  But all it takes is DC metro to be a degree or two colder to make a big difference in terms of accumulations.  

[winterymix]

The comments above about the importance of getting the flip to snow as early as possible are a big deal.

This is a strong storm but a really fast mover.  Below I've added simulated radar from the high def. NAM.

If true, snow is out of the area by 12Z/sunrise.

 

 

[Thanatos_I_Am]

3 minutes ago, WxWatcher007 said:

There will be a lot of cliff straddling today based on the HRRR. Get ready. 

Here in southern Moco? I'm sitting on the edge waiting for 12z to push me off.

[eurojosh]

1 minute ago, winterymix said:

The comments above about the importance of getting the flip to snow as early as possible are a big deal.

This is a strong storm but a really fast mover.  Below I've added simulated radar from the high def. NAM.

If true, snow is out of the area by 12Z/sunrise.

 

 

Right, and compare to the CMC on the other end of the spectrum where it is still snowing at 18z.

[H2O]

And for some reference(not saying this storm will be like it) but the Veterans Day storm of 1987 had temps in DC in the 60s the day prior.

[showmethesnow]

13 minutes ago, mitchnick said:

10z HRRR at 18 hours

 

 

Actually am liking your chances better this morning then I did just 24-36 hours ago. Think everything has been breaking the way we need to see to give you the best odds for seeing accumulation. The weak sauced low that the models were originally spitting out was never going to cut it especially when you were waiting for the cold to bleed in. Now we have a low that will rapidly intensify as it cuts underneath us giving us the dynamical cooling that will hopefully overcome the initial warm temps. Whether it is enough only time will tell. If we do see a change over I would not be surprised to see that it is a very rapid changeover from northwest to southeast. Whomever gets into that initial rapid changeover, as long as it occurs in the early part of the storm and not the tail end, I think has a good chance of seeing some half decent accumulations. 

[nj2va]

6z hi res RGEM for DC (temp at XXz and 3 hour ending precip):

6z 43 0.08"

9z 35 0.6" (925s are -2/850s -4)

12z 29 0.2"

Probably would be good for ~2" in DC but it'd be a pretty fun few hours given the heavy precip even if it's not accumulating the whole time  

 

[psuhoffman]

17 minutes ago, winterymix said:

That experimental HRRR looks plausible, it follows climatology and gives

PSU Carroll County land 7".   Book it.

It's got 8" right over my house. Don't short me. 

Obviously if the euro/rgem is right DC and Baltimore should get some accum. But even if things go towards a nam type track there is one thing to keep an eye on.  Once the low passes east of us heights will crash fast. The low is bombing and the trough going negative tilt. Both of those factors will aid in moisture transport to the left of the system. From there it's a race between the crashing temps and the back edge.  We've seen plenty times that last band flips and drops a quick 1-2". That's a nowcast type thing but it's not out of the question even if the nam more north track is correct. 

PS. You know you have a problem when auto correct changes them to rgem in all your texts 

[usedtobe]

16 minutes ago, H2O said:

And for some reference(not saying this storm will be like it) but the Veterans Day storm of 1987 had temps in DC in the 60s the day prior.

For us I'm still pessimistic.  We probably see some snow but I'm not convinced we see any accumulations.   The veteran's day storm was much different, it had a upper low closing off and was way more dynamic that this trough.  Most models have the precip pretty much done by 12z.  I don't trust the rgem as it has run cold every storm this year that I can think of except the first cold air damming ice storm.  The second one, it was way too cold.  Below I've attached the vet day storm surface and 500h.